Merge branch 'slashmanov/rapid-diffs-code-font-size' into 'master'

Update Rapid Diffs code sizings

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/182563



Merged-by: Martin Wortschack <mwortschack@gitlab.com>
Approved-by: Chaoyue Zhao <czhao@gitlab.com>
Approved-by: Martin Wortschack <mwortschack@gitlab.com>
Reviewed-by: Chaoyue Zhao <czhao@gitlab.com>
Co-authored-by: Stanislav Lashmanov <slashmanov@gitlab.com>

app/assets/stylesheets/components/rapid_diffs/_constants.scss

+$base-font-size: 16px;
+$code-row-height-target: 20px;
+$code-font-size-target: 12.5px;
+
+$code-row-height: calc($code-row-height-target / $base-font-size * 1rem);
+$code-font-size: calc($code-font-size-target / $base-font-size * 1rem);
+$code-line-height: calc($code-row-height-target / $code-font-size-target);

app/assets/stylesheets/components/rapid_diffs/text_file_viewers.scss

 @use 'highlight/common';
+@use 'constants';
 
 .rd-text-view-root {
   font-family: $monospace-font;
-  line-height: $code-line-height;
-  font-size: $code-font-size;
+  line-height: constants.$code-line-height;
+  font-size: constants.$code-font-size;
 }
 
 .rd-text-view-root,